1. Field of the Invention
This invention relates to a trigger mechanism, particularly for sports pistols, comprising a trigger lever, which carries a trigger blade and is biased by a spring having a variable initial stress and opposing the pull-off movement of the trigger lever, also comprising a sear, which cooperates with the trigger lever, and a catch lever, which is adapted to retain the spring-loaded striker and to interlock with the sear in a catching position, wherein the trigger lever is movable against the sear against the spring force.
2. Description of the Prior Art
In a known trigger mechanism of that kind (Feinwerkbau, Bedienungsanleitung-Instructions Modell 2), that arm of the trigger lever which extends away from the trigger blade extends into a mouth formed in the sear and bears on one of the legs defining that mouth. That leg is supported from below by an adjusting screw. The detent means for interlocking with the catch lever are provided on the forwardly facing side of the sear so that the latter constitutes a one-armed lever. That lever is provided with a rearwardly directed extension, which is engaged by a spring, which tends to rotate the sear against the adjusting screw and which cooperates with another adjusting screw. During the movement of the rearwardly extending lever arm of the trigger lever in the free space of the mouth of the sear the spring prevents a release of the catch which is in its catching position. The adjusting screw which is engaged by one of the mouth-defining legs serves only to change the overlap of the catch lever and the sear when they interlock, i.e., to change the pull-off resistance. The initial angular movement of the trigger blade and trigger lever to the pull-off position is defined only by the width of the mouth formed in the sear and undesirably cannot be changed. The additional adjusting screw which cooperates with the rearwardly directed extension of the sear serves to limit the pivotal movement performed by the trigger lever to a position over the sear under the spring force. That additional adjusting screw thus constitutes a so-called trigger stop. The spring which biases the sear obviously increases the structural expenditure.
DE-A-No. 2 053 006 discloses a trigger mechanism in which the trigger lever is formed with an axially adjustable pull-off cam, which extends toward the overlying arm of the sear, and an advancing cam. The pivot for the trigger lever is movably mounted in a positioning plate, which is displaceable relative to the housing of the trigger mechanism approximately in the direction of the forwardly directed arm of the sear and can be fixed in position. Upon a displacement of the positioning plate the advancing cam will slide on the associated arm of the sear and the distance between the advancing cam and the pivotal axis of the sear will be changed as well as the lever ratio of the sear and the force which is required to release the round, i.e., the so-called trigger pull weight. But the positioning plate and the associated clamp screw add to the structural expenditure and the weight of the shooting arm. Besides, it is difficult to effect an exact adjustment. The initial angular movement of the trigger blade and trigger lever to the pull-off position undesirably cannot be changed. Whereas it is also known to provide a mouth in the sear of a trigger mechanism (CH-A-No. 499 766), that mouth acts directly on the catch lever and also cannot be adjusted. In both cases the overlap of the interlocking members cannot be changed to influence the pull-off resistance.